The present invention concerns a procedure for modernizing the control system of a lift group, in the procedure the group control system coordinating the functions of the lifts being renovated and connected to an already existing lift-specific control system.
When old lift groups are being modernized it is desirable that the changes of the control system can be accomplished in one lift or, in big groups, in a few lifts at a time so that the lift service is disturbed as little as possible. In this way, long waiting times can be avoided which are incurred when the disconnected lifts lower the capacity of the lift group.
Since disconnection cannot be entirely avoided, the best solution is to proceed by steps in the modernizing process in the way that the first step is directed to improving the efficiency of the group control utilizing the facilities offered by new technology, applying them so that no disturbances are caused in the house during transition, while at the same time the advantage in transport capacity gained from the change is maximized.
Known in the art are procedures in which normal control systems designed for new houses are used and the control system of the lift group is modernized by steps in the way that one lift or a few lifts at a time are taken out of service. In accordance with such solutions, all changes on the control of one lift are made at one time and in the case of several lifts, totally or partly in parallel. It is thus understood that the new group control is installed and connected in parallel with the old control to control the lifts which have already been modernized.
This results in several drawbacks:
The transport capacity available in the building is remarkably lowered for the duration of the changes; for instance, in a group of four lifts the transport capacity drops to one half, since usually two lifts at a time are disconnected. One has to bear in mind that this phase during which the transport capacity is considerably reduced lasts for several months as a rule.
In addition, said procedure has the remarkable drawback that in big lift groups in which the work is carried out in more than two phases, there will be a long transition period during the changes in which the whole lift group is controlled by two different group controls. This results in several drawbacks:
First, coordination is incomplete, resulting in reduced capacity and longer waiting times in comparison with the situation in which there is the same number of lifts available and they are controlled by one group control. Secondly, in this kind of situation the landings usually have two sets of call buttons because owing to differences in technology it is not worth while to connect together temporarily the group controls representing two different generations; as a consequence, the passengers will as a rule press the button of both systems, "to make sure", whereby both group controls will dispatch a lift to the landing in question, and this results in even further reduction of capacity and longer waiting times.
Also known in the art are control systems specifically intended for modernizing jobs, and associated modernizing procedures. They are based on replacement of the old group control by a new, microcomputer- based system including a powerful microcomputer to which the input and output data required in controlling all old lifts are directly connected.
To this end, the control system contains a great number of voltage adapters, e.g. in a lift group of medium size up to a thousand units. In order to minimize the work required by the change, the old lift- specific control and adjustment means are only altered enough to enable the requisite signals to be exchanged between the old system and the new system.
This procedure has the drawback that further modernizing becomes difficult. To wit, when in the future the lift-specific controls are replaced by new technology, the connections to the group control which has been changed once already have to be changed again, because the adapter circuits for its signals were in their time matched to the structural and operational principles applied in control systems implemented with relay, transistor or discrete logic circuitry.
Apart from the fact that the voltages are higher in old systems and they are frequently a.c. voltages, the principles of operation are greatly different owing to the use of electromechanical ancillaries, such as the floor selector for instance. Maintaining the voltage and data definitions of the signals of the old designs in new products involves technical problems and extra costs and, in the long run, spare part and training problems in the service department. When solving these problems, the designer must moreover make compromises, with the result that all benefits afforded by modern technology cannot be utilized.
Another significant drawback of systems intended exclusively for modernizing is their restricted traffic technological performance and their inflexibility with reference to single needs of change arising for instance out of changed regulations. It is obvious that the deficiencies of the basic system remain in the main, since improved systems of this type do not yet perform any optimation of call distributing. The call distributing principles are complicated and slow to develop, and therefore it has usually only been possible to upgrade the principles of operation of the systems at those points where the computer could be applied in a simple manner to improve the principles of the old-fashioned system already in use, e.g. to recognize certain traffic situations and excessive waiting times and to carry out supplementary action accordingly.